A few weeks ago, I noticed our cat Olaf had gotten… let’s just say a bit too comfortable with his lazy lifestyle. Eat, sleep, repeat. Elsa noticed too, and suggested we get him some kind of moving toy to encourage him to play. We looked at a few of the automatic cat toys online — and honestly, some of them cost more than I’d like to admit.

We happened to have some M5Stack parts lying around from an earlier project, so Elsa said: why not just build one ourselves?

From that point on, it was pretty much her show. The “monster” concept — dressing up a circuit board in white faux fur and cardboard horns so it wouldn’t look scary to Olaf — was entirely her idea. Later, when the arm’s movement felt too robotic to actually catch a cat’s attention, she figured out on her own that it needed to “freeze” like it was hiding, then suddenly dart, mimicking how real prey moves. My contribution was mostly limited to buying parts and general logistics.

The end result is the “Laser Cat Monster” — it gently wiggles a laser dot when nothing’s around, and the moment it senses Olaf getting close, it switches into full play mode, waving its arm and darting the laser around to get him moving.

Whether Olaf is actually impressed is still up for debate. But watching an 11-year-old go from “we should fix this” to actually building something that works — that part I’m genuinely proud of.

Full project details, code, and demo video are here if you’re curious: 👉 https://www.hackster.io/elsakong/laser-cat-monster-to-keep-my-cat-fit-12c687